Soybean (Under development)

Scientific Name
Glycine max
Order / Family
Fabales: Fabaceae
Other pests: Couch grass, Leafhoppers, Sedges

Geographical Distribution in Africa

Geographical distribution of Soybean in Africa. Updated on 26 April 2019. Source FAOSTAT.

General Information and Agronomic Aspects

Soybean is the world's most important legume in terms of production and trade due to its high content of protein (35-40 %) and oil (15-22 %). Soybean products are rich in essential amino acids, vitamins and minerals. Soybeans are used in the preparation of a variety of fresh, fermented and dried food products like milk, tofu, soya sauce and bean sprouts. Soybeans are used not only for food but they serve also as a cure for various diseases and body ailments. Soybeans (preferably black ones) are included in medicines to improve the function of the heart, liver, kidneys, stomach and bowels. They are also processed to extract oil for food and for numerous industrial purposes. As edible oil, it enters the market as salad oil, cooking oil, margarine and shortening. Soybean meal is extensively used as an ingredient in livestock feed. 
Soybean is also one of the crops where many varieties are now genetically modified - especially in the American market. 
In sub-Saharan Africa, soybean is mostly grown by small-scale farmers either as a sole crop or mixed with sorghum, maize or cassava. 

Nutritive Value per 100 g of edible Portion

Raw or Cooked Soybean Food
Energy
(Calories / %Daily Value*)
Carbohydrates
(g / %DV)
Fat
(g / %DV)
Protein
(g / %DV)
Calcium
(g / %DV)
Phosphorus
(mg / %DV)
Iron
(mg / %DV)
Potassium
(mg / %DV)
Vitamin A
(I.U)
Vitamin C
(I.U)
Vitamin B 6
(I.U)
Vitamin B 12
(I.U)
Thiamine
(mg / %DV)
Riboflavin
(mg / %DV)
Ash
(g / %DV)
Soybean Oil 884 / 44% 0.0 / 0% 100.0 / 154% 0.0 / 0% 0.0 / 0% 0.0 / 0% 0.0 / 0% 0.1 / 0% 0.0 IU/ 0% 0.0 / 0% 0.0 / 0% 0.0 / 0% 0.0 / 0% 0.0 / 0% 0.0
Green Soybeans cooked 141 / 7% 11.1 / 4% 6.4 / 10% 12.3 / 25% 145 / 14% 158 / 16% 2.5 / 14% 539 / 15% 156 IU / 3% 17.0 / 28% 0.1 / 3% 0.0 / 0% 0.3 / 17% 0.2 / 9% 1.6
Green Soybeans raw 147 / 7% 11.1 / 4% 6.8 / 10% 13.0 / 26% 197.0 / 20% 194.0 / 19% 3.6 / 20% 620.0 / 18% 180 IU / 4% 29.0 / 48% 0.1 / 3% 0.0 / 0% 0.4 / 29% 0.2 / 10% 1.7
Soybeans mature cooked 173.0 / 9% 9.9 / 3% 9.0 / 14% 16.6 / 33% 102.0 / 10% 245 / 24% 5.1 / 29% 515.0 / 15% 9.0 IU / 0% 1.7 / 3% 0.2 / 12% 0.0 / 0% 0.2 / 10% 0.3 / 17% 1.9
Soybeans mature raw 446 / 22% 30.2 / 10% 19.9 / 31% 36.5 / 73% 277 / 28% 704 / 70% 15.7 / 87% 1797 / 51% 22.0 IU / 0% 6.0 / 10% 0.4 / 19% 0.0 / 0% 0.9 / 58% 0.9 / 51% 4.9
Soybeans mature roasted 471 / 24%2% 33.5 / 11% 25.4 / 39% 35.2 / 70% 138.0 / 14% 363.0 / 36% 3.9 / 22% 1470.0 / 42% 0.0 / 0% 2.2 / 4% 0.2 / 10% 0.0 / 0% 0.1 / 7% 0.1 / 9% 3.9
Soybeans sprouted cooked 81.0 / 4% 6.5 / 2% 4.5 / 7% 8.5 / 17% 59.0 / 6% 135.0 /14% 1.3 / 7% 355 / 10% 40 IU / 1% 8.3 / 14% 0.1 / 5% 0.0 / 0% 0.2 / 14% 0.1 / 3% 1.1
Soybeans sprouted raw 122 / 6% 9.6 / 3% 6.7 / 10% 13.1 / 26% 67.0 / 7% 164.0 / 16% 2.1 / 12% 484 / 14% 11.0 IU / 0% 15.3 / 26% 0.2 / 9% 0.0 / 0% 0.3 / 23% 0.1 / 7% 1.6

*Percent Daily Values (DV) are based on a 2000 calorie diet. Your daily values may be higher or lower, depending on your calorie needs. 
 

 

Climate conditions, soil and water management

Soybean is grown from the Equator to latitude 55°N or 55°S, and from below sea level to altitudes close to 2000 m. Above 2000 m the late maturing varieties take as long as 180 days (6 months) but they out-yield the early maturing varieties. Soybean is a short-day plant. In Kenya, soybeans are grown in the maize growing areas, mainly by small-scale farmers. 
Temperatures below 21°C and above 32°C can reduce floral initiation and pod set. Extreme temperatures above 40°C are detrimental for seed production. 
If water is available, soybeans can be grown throughout the year in the tropics and subtropics. Soybean requires 400 to 500 mm in a season for a good crop. High moisture requirement is critical at the time of germination, flowering and pod forming stage. However, dry weather is necessary for ripening. Soybeans can tolerate brief water logging but weathering of seed is a serious problem in the rainy season. 

Soybeans are sensitive to low pH. In acid soils, liming is essential to raise the pH to 6.0 or 6.5 and to obtain optimum yield. Manganese (Mn), iron (Fe) and aluminum (AI) toxicity is common with low pH, and deficiency in Mn and Fe with high pH. Cultivars tolerant to iron deficiency are available. 

 

Propagation and planting

Soybeans are propagated by seed. However soybean seed looses viability within 6-10 months depending on the variety and the environmental conditions, especially under hot and damp conditions. Test seed for viability before planting: take 100 seeds from about 3 places in the seed lot, put each lot of 100 seed in a glass of water for 24 hours, then drain off the water and replace with damp cotton wool or a damp cloth. Keep cloth damp - after 3-4 days young sprouts will have formed on all viable seed, and it is easy to count how many out of the 100 that has germinated (germination percent). Germination percent above 85 is regarded good. They are grown on paddy-rice bunds too. Soybeans are sown without tillage in rice stubble after each harvest in rows with a spacing of 25 x 25 or 20 x 20 cm. In tilled fields, soybeans are sown in rows 40-50 cm apart and within rows the seeds are either drilled or planted 10 cm apart. Seed rate is 60-70 kg/ha. Broadcasting of seed after the rice harvest is also practised. 

Examples of different soybean varieties grown in Kenya and their parameters: 

 

Characteristics/ varieties Production altitude (masl) Days to physiological maturity Seed yield kg/ha Oil content (%) Protein content (%)
Black Hawk 800 -1700 150-165 1.8 18 35
EAI 3600 800-1700 53-142 0.5-2.5 17.8 35    
Gazelle 1200-2400 73-175 0.8-2.1 22 35    
Hill 1200-2400 140-145 1.8 20.7 33    
Nyala 1200-2400 82-163 0.7-2.5 17 33    
DPSB 19 900-2400 90-120 0.6-1.7        
DPSB 8 900-2400 120-150 0.5-2.6 18 38    
Kensoy009 Cool warm weather 120-150 1.5-3.0        
SC Saga 1000-1800 90-120 2.5-4.5 20-22 37-40    
SCS 810/6/26SC (Salama) 1000-1500 90-120 2.0-4.0 20 40    
         

Source: KEPHIS National Plant Variety List

 

Soybean green pods
Soybean green pods

© A. A. Seif, icipe

 

 

Soybean plant close-up of foliage

Soybean plant close-up of foliage

© A. A. Seif, icipe

 

 

Soybean plants
Soybean plants

© A. A. Seif, icipe

 

 

Recommended soybean varieties for different agro ecological zones in Kenya: 

Description Area in Kenya Varieties
Warm temperature sites Homa Bay "Duicker", "EAI 3600" and "Nyala"
Moderate temperature sites Bukura, Kakamega, Embu "SCS I", "Duicker", "Nyala" and "Gazelle"
Cool temperature sites Bahati, Baraton, Menengai "Sable", "SCS I", "Nyala" and "Gazelle"
Marginal rainfall sites Matayos, Gachoka, Makueni, Ol Rongai "Gazelle", "EAI 3600", "Nyala" and "Sable"

 

Recommended soybean variety in Tanzania

  • "Soya Uyole 1" (optimal production altitude: 1000-1800 m; grain yield per ha: 1500-3000 kg; resistant to lodging and shattering)

 

Recommended soybean varieties in Uganda:

  • "Maksoy 1N" (maturity: 95 days; yield per ha: 2000 kg; resistant to soybean rust, lodging and pod shattering; good for intercropping)
  • "Namsoy 4M" (maturity: 100 days; yield per ha: 2000 kg; resistant to soybean rust, lodging and pod shattering; good for intercropping)
  • "MNG 8.10" (yield per ha: 2500 kg; resistant to soybean rust)

 

Intercropping

Soybeans are cultivated both as a sole crop and in various intercropping systems with maize, cassava, sorghum, banana, sugar-cane, rubber, oil palm, coconut and fruit-trees. In maize and sorghum, soybeans can be intercropped with two rows. 
Intercropping soybean with maize attracts parasitic wasps that control African bollworm (Helicoverpa armigera) and at the same time serves as weed cover. Soybeans should not be grown on the same site for more than two years to prevent a build-up of soil-borne diseases. Practise crop rotation of 3 to 4 years as a part of disease control. The plant grows best in a rotation after maize or small grains but should not follow edible beans, rape, or sunflowers because white mould disease can be carried over. 
 

 

Husbandry

Weed control is essential. Early seed bed preparation with removal of couch and watergrass is the first step to good yields. Irrigation at flowering and during seed filling is essential to gain optimum yield. More frequent irrigation is needed in sandy, well-drained soils than in heavy clay soils. Favourable effects of soybeans are improved soil structure and fertility due to its nitrogen fixing capacity. Soybeans can obtain all of their nitrogen needs from the air when nitrogen-fixing-rhizobia (bacteria) are present in the soil. Nitrogen fixation is a result of the symbiotic relationship of rhizobia and the plants. Where soybeans have not been grown before it may be beneficial to treat the seed with soybean inoculum (Rhizobium japonicum), available from University of Nairobi - Kabete campus, Dept. of Soil Science) at a rate of 100 g/15 kg seed before planting to allow maximum nitrogen fixing throughout the growing season. A well-nodulated plant should have around 5-7 nodules on the primary root. When plants have fewer nodules, monitor the field carefully to determine if the nodule numbers increase. Nitrogen deficiency results in reduced chlorophyll development and a pale-green leaf colour. Do not add nitrogen to well-nodulated soybeans. It is just a waste of time and money. Nitrogen added during planting delays nodulation and when applied during the vegetative stage results in poor nodule formation in proportion to the rates applied. However phosphorus in the form of rock phosphate at a rate of about 100-150 kg/ha is very beneficial for good root formation. 
 

 

Harvesting

Early-maturing cultivars can be harvested for grain 70 days after planting and late maturing cultivars need up to 180 days. The plants are cut near the ground or pulled with their roots at physiological maturity when most leaves have aged and turned yellow, and at least one pod per plant have turned brown or black. Vegetable soybeans are harvested when the pods are still green but when the seeds have filled the pod. Most small scale farmers achieve yields of about 500-1000 kg/ha, though 3000 kg/ha is possible with good husbandry practices and recommended varieties. 
Soybeans can be harvested by hand or by combine harvesters (this only at full maturity or after windrowing - cutting plants and leaving them in rows for wind and sun to dry properly). Once threshed, dry the soybeans to below 12% moisture content before storing. Keep in a clean store and prevent weevil attack by any of the means described under storage pests. Seeds meant for seed should not be stored for longer than 1 year due to rapid loss of germination capability.

For more information on storage pests click here 

Information on Diseases

Among the diseases, Soybean rust caused by Phakopsora pachyrhizi can reduce yields by as much as 90%.
Other serious diseases are: Bacterial pustule (Xanthomonas axonopodis pv. glycines) /Soybean bacterial blight (Pseudomonas savastonoi pv. glycinea), Soybean downy mildew (Peronospora manshurica), Anthracnose (Colletotrichum truncatum and Glomerella glycines), Purple seed stain (Cercospora kikuchii), Pod and stem blight (Diaporthe phaseolorum var. sojae), Soybean mosaic potyvirus, Bean yellow mosaic virus and various seedling diseases.

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